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The "Santa Rosa" plum tree (Prunus salicina "Santa Rosa") is a deciduous plum tree that has white spring blooms and dark red summer fruit. The tree grows up to 30 feet tall in U.S. Department of Agriculture plant hardiness zones 5 through 9. "Santa Rosa" needs full sun and a well-draining soil, as well as weekly watering until it is established and an early spring application of a general purpose fertilizer. Even with proper care, an occasional disease may infect the plum tree.

Brown Rot

Brown Rot (Monilinia spp.) affects the fruit, flowers and twigs of the plum tree. Flowers will turn brown and dry up, but they do not fall from the tree. Brown spots develop and spread over fruit, followed by lighter colored spores. Where the flowers attach to the twigs, sunken areas and brown sticky goo appear and the leaves at the ends of the twigs shrivel. Prune out diseased branches, and avoid getting the foliage wet when watering to help limit the disease. A copper-containing fungicide can be applied after buds appear, but before the tree blooms.

Bacterial Canker

Bacterial canker (Pseudomonas syringae) appear as dark brown water spots on the bark of trees. The spots secrete a sticky substance in the spring. The cankers can also spread to the other parts of the tree, causing sunken spots on leaves and fruit as well as brown, shriveled blossoms. Symptoms are more widespread in periods of cool, wet weather. Prevent the disease by planting in deep, well-draining soil, practicing dormant winter pruning and applying macronutrients in the spring. Remove infected limbs in the summer at least 6 inches below the canker into healthy wood.

Plum Leaf Scald

Plum leaf scald (Xylella fastidiosa) is a type of bacterial leaf scorch that causes leaves to look burned or brown around the edges. If enough of the foliage is infected, the tree eventually declines and dies. The bacteria that causes leaf scald is spread by leafhoppers. Once the tree is infected, nothing can be done to eradicate the disease. Pruning infected limbs can help slow the spread. Keeping the tree healthy will make it less likely to develop the disease.

Black Knot

Black knot (Apiosporina morbosum) is a fungus that causes black galls to form on smaller limbs and twigs of the plum tree. The galls begin to form after the tree blooms, and they spread along the branches. In the fall, the black knots harden. Trees can live for several years with the disease; but if too many limbs are girdled, it could eventually die. Remove infected limbs in the winter at least 4 inches past the galls into healthy wood. Use a copper-containing fungicide in the spring before the buds open to help control the disease.

About the Author

Jill Kokemuller has been writing since 2010, with work published in the "Daily Gate City." She spent six years working in a private boarding school, where her focus was English, algebra and geometry. Kokemuller is an authorized substitute teacher and holds a Bachelor of Arts in English from the University of Iowa.